1. Field of the Invention
The present invention relates to a process for regenerating a catalyst of the type used in hydrocarbon conversion processes. More particularly, this invention relates to a process for regenerating a catalyst that has become deactivated or partially deactivated by the formation of stable, catalytically inert complexes during contact with a hydrocarbon feedstock, said catalyst comprising (a) one or more Lewis acids of the formula MX.sub.n where M is a component selected from Group IIIA, IVB, V, VIB or VIII Elements of the Periodic Table or their mixtures, X is a halogen, n is the atomic ratio of halogen to M and varies from 1 to 8, and (b) a strong Bronsted acid, by contacting said catalyst with either a halogen or a hydrogen halide and fluorine.
2. Description of the Prior Art
It is well known in the prior art that the activity of Friedel Craft's type hydrocarbon conversion catalysts declines gradually due to the accumulation of various contaminants or poisons, such as compounds of carbon, sulfur, nitrogen, oxygen, metals, water and the like, until the catalysts cease to exhibit an economic activity. In such cases, depending upon economic factors, the catalyst may be replaced or regenerated to restore desired activity levels.
Several methods have been suggested for regenerating Friedel-Craft's hydrocarbon conversion catalysts via halogenation. For example, U.S. Pat. No. 2,709,688 teaches the regeneration of spent aluminum or zirconium fluoride catalysts by contact with chlorine trifluoride. U.S. Pat. No. 2,113,028 discloses the regeneration of spent double halide catalysts by contacting same with a halogen. In addition, U.S. Pat. No. 2,488,744 teaches the removal of metal contaminants from a silica-alumina cracking catalyst using a mixture of hydrogen chloride and chlorine. U.S. Pat. No. 3,369,862 discloses that stable, catalytically inert hexafluoroantimonic acid complexes can be decomposed to antimony trifluoride and lower molecular weight hydrocarbons, with the antimony trifluoride then being converted to antimony pentafluoride or directly to hexafluoroantimonic acid by treatment with florine or chlorine and hydrogen fluoride. U.S. Pat. No. 3,809,728 teaches regenerating a supported hydrogen fluoride-antimony pentafluoride catalyst with liquid hydrogen fluoride and then recontacting the catalyst support with a liquid solution of hydrogen fluoride antimony pentafluoride. However, none of the foregoing prior art discloses a method for regenerating the catalyst system described hereinafter using a halogen or a hydrogen halide and fluorine.